Polarised vs Non-Polarised Capacitors

[digitalsea]

Hey all,

I’ve been looking a at few pedal designs and it seems that some designers have used non-polarised electrolytic caps in their circuits.
To my uneducated eyes, it looks as though a normal polarised cap would would in it’s place, but obviously the designer would use a common component if it was a straight swap. This would mean that non-polarised make a difference.

Can someone explain why you would use a non-polarised over a polarised?

Thanks for the help

 

[Chuck D. Bones]

Non-polarized aluminum electrolytics are typically optimized for and used in high-end audio applications. There are two or three reasons why they would be used in pedals:
1. The pedal designer wanted the small footprint of an aluminum electrolytic.
2. The voltage drop across the capacitor can assume both polarities in the circuit.
3. Snob appeal.

You can always safely sub a non-polarized in place of a polarized capacitor. You can only sub a polarized in place of a non-polarized if you can be sure that the voltage will always be one polarity and you orient the capacitor on the board in accordance with that polarity.

I have seen circuits that contained polarized capacitors and should have had non-polarized. I have also seen a few where one or more polarized cap
was installed backwards. While it's never a good idea to do either of those things, people get away with it if the reverse voltage is under 1V, the circuit is insensitive to current leaking thru the cap and the temperatures are not too severe.

Always make sure you observe the proper voltage rating.